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William Aird: Standardizing Anemia, Thrombocytopenia, and Neutropenia Cutoffs

William Aird/X

Sep 23, 2025, 06:36

William Aird: Standardizing Anemia, Thrombocytopenia, and Neutropenia Cutoffs

William Aird, Professor of Medicine at Harvard Medical School, posted on X:

“MILD, MODERATE, SEVERE… ACCORDING TO WHO?

I often notice MDs describing cytopenias as “mild,” “moderate,” or “severe” without reference to standard definitions.

The problem? Severity is in the eye of the beholder. Without shared definitions, these terms lose precision.

Of course, no one will argue if you call a platelet count of 143k “mild.”

But in teaching, communication, and especially clinical trials, it’s important to anchor our language to standardized thresholds so we’re all speaking the same language.

The graphic in this tweet summarizes commonly used cutoffs for anemia, thrombocytopenia, and neutropenia, based on guidelines and consensus in the literature.

Clear definitions help keep us on the same page, in both patient care and research!

As much as I endorse standardized definitions, I’d find it more helpful if “severe anemia” aligned better with our transfusion threshold (~7 g/dL). Also, there’s a big difference between a hemoglobin of 7.9 (severe by WHO) and 4.0 in the ED. How ’bout a bit more granularity?”

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